Portable shears



J.ARTRU ETAL 3,350,780

` PORTABLE sHEARs Nov. 7, 1967 Filed May 15, i966 nml ovrl. E mi m@ United States Patent O M' 3,350,780 PORTABLE SHEARS Jean Artru and Edmond Vignal, both of Route de Peyrus, Chabeuii, France Filed May 13, 1966, Ser. No. 549,855 2 Claims. (Cl. 311-228) ABSTRACT F THE DISCLOSURE Pruning-shears include a cylinder body mounting a piston having a rod with a rack thereon. The rack meshes with a toothed sector which is mechanically connected to a pivotal shear blade through segmental gears within a liat casing. Fluid pressure actuates the piston for cutting stroke of the shears and a spring return is provided. A trigger on the body controls electrohydraulic operation.

This invention relates to shears used for pruning trees and similar operations and it has for its object to provide pruning-shears which will be simple in construction While being capable of easily cutting branches of substantial diameter.

Another object of this invention is to provide pruningshears comprising a fluid-actuated movable blade.

In a preferred embodiment of the present invention the pruning-shears comprise a `body having a cylindrical longitudinal bore in which is slidably mounted a piston provided with a rod whose outer end is in the form of a rack adapted to actuate a toothed sector which is in turn mechanically connected with the movable blade of the shears by a pair of segmental gears. In such an arrangement the cutting stroke of the movable blade may be effected by nid pressure with any desired ratio between the angular displacement of the movable blade and the rectilinear displacement of the piston, while the return stroke may be insured by a spring conveniently disposed within the hollow cylindrical body so as to act on the piston itself.

The blades of the pruning-shears are preferably sup ported by a relatively llat casing in which the transmission gearing between the piston rod and the movable blade is disposed. The hollow body forms the handle portion of the shears and it is provided with a trigger adapted to actuate a micro-switch which in turn controls the solenoid of an electromagnetically operated valve so as to connect the tool either to the outlet of a pump or to the corresponding tank or sump, the connection between the pruning-shears and the valve being effected by means of a hose and of an electric cable associated therewith.

In the annexed drawings:

FIG. 1 is a plan view of -a preferred embodiment of the present invention.

FIG. 2 is a longitudinal section thereof taken along line II-II of FIG. 1.

FIG. 3 is a transverse section taken along line III-III of FIG. 2.

FIG. 4 diagrammatically shows the hydraulic and electric circuits.

Referring to FIGS. 1 and 2 the pruning-shears comprise a hollow body 1 and a fiat casing 2 formed of two halves 2a and 2b which are secured to body 1 by means of bolts such as 3. Body 1 is adapted to form the handle of the tool and the actuating ram thereof, as more fully explained below.

Body 1 has an inner cylindrical bore 1a which is closed at its end farthest from casing 2 by a partition 4. Within this bore 1a is retained a sleeve 5 adapted to accommodate a slidably mounted piston 6, having a rod 7 which extends into casing 2. Piston 4 is provided with a cup-shaped seal 8 and with a boss 9, this later being screwed on the 3,359,736 Patented. Nov. 7, 1967 ICC protruding inner end of rod 7. Between boss 9 and a Washer 11 which bears against the partition 4 by means of a ball 12, there is disposed a compression spring 10 which thus urges piston 6 towards casing 2. The end of bore 1a opposed to partition 4 is closed by a plug 13 which is secured in position by screws 14. This plug 13 has an axial bore for passage of rod 7` and its inner end is provided with an annular gutter-shaped seal 15 which bears on the periphery of the rod.

Above the aforesaid bore 1a body 1 has a longitudinal duct 1b which is connected by a coupling 16 of any conventional construction with the end of a liexible hose 17. The front end of duct 1b communicates through an opening 1c with bore 1a, close to the inner end of plug 13. When therefore a iluid such as oil is forced under pressure into hose 17, it flows through duct 1b and acts on piston 6 against spring 10, the air present in the chamber comprised between piston 6 and partition 4- escaping through an appropriate vent-hole provided in said partition 4.

The outer end of rod 7 is in the form of a rack, as indicated at 7a and it meshes with .a segmental gear 18a which forms the rst portion of a double sector 18 rotatably carried by a transverse pin 19 mounted in the flat casing 2. This pin 19 at the same time forms a bolt which maintains against each other the halves 2a, 2b of casing 2. The second portion of sector 18 is in the form of another segmental gear 18h of smaller diameter than segmental gear 18a. This smaller segmental gear 18b meshes with a toothed sector 20 secured by screws such as 21 onto the heel portion of a movable blade 22 which is rotatably supported by a transverse pin or bolt 23. This movable blade 22 cooperates with a fixed blade 24 which is retained within half 2b by a clamping plate 25 formed with a cylindrical boss adapted to maintain halves 2a and 2b at the proper distance from each other. As clearly shown in FIG. 3 this boss receives an axial bolt 26 by means of which plate 25 and blade 24 are clamped between the lateral walls of halves 2a and 2b.

Rack 7a is maintained in proper meshing engagement with segmental gear 18a by means of an upper bearing or roller 27 supported by the halves 2a and 2b of casing 2. The upper side of rack 7a is formed With -a flat portion 7b in order to increase the contacting area between the said rack and bearing or roller 27.

A rectangular box 28 is secured to the rear side of body 1 against partition 4. Within this box 2S is mounted a block 29 of insulating material which carries two parallel plugs adapted to cooperate with a correspond ing bi-polar socket 30; the electric cable 31 which is associated with socket 3) is combined with hose 17. The aforesaid plugs are connected through vertical conductors 32 with a micro-switch 33, secured to block 29. The actuating member 33a of switch 33 is axially actuated by a longitudinal rod 34, slidably mounted in an axial bore 1d provided in body 1, below bore 1a. A small spring 35 tends to maintain the front end of rod 34 against an appropriate tooth formed on a trigger 36, pivoted on a pin 37 transversely mounted in a recess 1e provided on the underside of casing 1. A blade spring 37, appropriately curved, acts for maintaining the switch 33 at the position of rest illustrated in FIG. 2; at this position switch 33 is open and it is only brought to the closed position when trigger 36 is raised into recess 1e.

FIG. 4 diagrammatically illustrates the general arrangement of the stationary parts adapted to supply fluid under pressure to the portable shears of FIGS. l to 3. The electromagnetic valve 39 is actuated by a solenoid 46 which is disposed in series `with the micro-switch 33 through cable 31. Valve 39 is of conventional construction and a very `brief description thereof will therefore be sufficient. Its inner movable part is actuated by the aforesaid solenoid 46 against the action of a returning spring 39a. Its inner space is connected with the tank or sump 40 of the hydraulic system by means of two conduits 4I and 42, The outlet of the pump 43 is connected with the said valve by two conduits 44 and 45. When the operator actuates trigger 36, he closes micro-switch 33, the solenoid 46 of the vaive 39 lowers the movable part of this latter whereby hose I7 is connected with conduit 44 while conduits 4l, 4S and 42 are isolated. The oil under pressure iiows as indicated by the arrows in dash lines in FIG. 4 and it therefore pushes piston 6 towards the right in FIG. 2 Owing to this movement of piston 6, sector 18 is rotated clockwise by rack 7a and therefore the movable blade 22 of the shears rotates counterclockwise, thus cutting the branches or twigs inserted between the blades of the shears.

As soon as the operator releases trigger 36 the movable part of valve 39 is raised by spring 39a (position illustrated in FIG. 4). Hose 17 now communicates with conduit 41 and spring 1t) may return piston 6 towards the left, the oil iiowing as indicated by the arrows in full lines. It will be observed that at this position of valve 39 conduits 45 and 42 are connected with each other so that the outlet of pump 43 is directly returned to tank or sump 40.

We claim:

1. Portable shears comprising an elongated body forming a handle for said shears, said body having a rst end and a second end and having a longitudinal bore extending therethrough, said bore also having a first end and a second end respectively corresponding to said rst and second ends of said body; means to close said rst end of said bore; a piston slidable within said bore; a rod axially disposed with respect to said bore, said rod having one end secured to said piston and slidably extending beyond said first end of said bore through said means, the portion of said rod remote from said piston and exterior to said bore being formed as a rack; duct means extending through said body from said first end of said bore to said second end of said body to be connected with an appropriate iuid distributor; a compression spring disposed within said bore between said piston and said second end of said bore to urge said piston towards said first end of said bore; means -at said second end of said bore to form a rest for said compression spring; a substantially fiat casing secured to said first end of said body and housing said rack portion of Said rod; a double segmental gear embodying a first toothed segment in mesh with said rack portion of said rod and a second toothed segment of smaller radius than said first segment and angularly solid therewith, said double segmental gear being rotatably carried within said casing; means carried by said casing to guide said rod and to maintain the rack portion thereof in mesh with said first toothed segment of said double segmental gear; a movable cutting blade rotatably carried by said casing and projecting outwardly therefrom; a toothed sector secured to said movable cutting blade co-axially thereto to mesh with said second toothed segment of said double segmental gear; a fixed cutting blade secured within said casing and projecting outwardly therefrom for cooperation with said movable cutting blade; a switch carried by said body at said second end thereof; a rod longitudinally carried by said body to actuate said switch; and a spring-loaded trigger pivoted to said body near said first end thereof to actuate said rod.

2. Portable shears comprising a support; a fixed cutting blade carried by said support; a movable cutting blade rotatably carried by said support to cooperate with said iixed cutting blade; a toothed rack slidably carried by said support to actuate said movable cutting blade; a first segmental gear in mesh with said rack, said lirst segmental gear being rotatably carried by said support and having a first radius; a second segmental gear coaxial t0 said first segmental gear and angularly solid therewith, said second segmental gear having a second radius different from said first radius; a toothed sector coaxial to said movable cutting blade and angularly solid therewith, said toothed sector being in mesh with said second segmental gear to be driven thereby; and iiuid power means carried by said support to actuate said toothed rack.

References Cited UNITED STATES PATENTS 2,224,708 12/1940 Sittert 30--228 X 2,763,060 9/1956 Swanson 30-228 2,818,643 1/1958 Dawson 30-228 3,177,584 4/1965 Cockerill 30-228 3,210,844 10/1965 Tontscheff E50-250 WILLIAM FELDMAN, Prima/y Examiner.

J. C. PETERS, Assistant Examiner. 

1. PORTABLE SHEARS COMPRISING AN ELONGATED BODY FORMING A HANDLE FOR SAID SHEARS, SAID BODY HAVING A FIRST END AND A SECOND END AND HAVING A LONGITUDINAL BORE EXTENDING THERETHROUGH, SAID BORE ALSO HAVING A FIRST END AND A SECOND END RESPECTIVELY CORRESPONDING TO SAID FIRST AND SECOND ENDS OF SAID BODY; MEANS TO CLOSE SAID FRIST END OF SAID BORE; A PISTON SLIDABLE WITHIN SAID BORE; A ROD AXIALLY DISPOSED WITH RESPECT TO SAID BORE, SAID ROD HAVING ONE END SECURED TO SAID PISTON AND SLIDABLY EXTENDING BEYOND SAID FIRST END OF SAID BORE THROUGH SAID MEANS, THE PORTION OF SAID ROD REMOTE FROM SAID PISTON AND EXTERIOR TO SAID BORE BEING FORMED AS A RACK; DUCT MEANS EXTENDING THROUGH SAID BODY FROM SAID FIRST END OF SAID BORE TO SAID SECOND END OF SAID BODY TO BE CONNECTED WITH AN APPROPRIATE FLUID DISTRIBUTOR; A COMPRESSION SPRING DISPOSED WITHIN SAID BORE BETWEEN SAID PISTON AND SAID SECOND END OF SAID BORE TO URGE SAID PISTON TOWARDS SAID FIRST END OF SAID BORE; MEANS AT SAID SECOND END OF SAID BORE TO FORM A REST FOR SAID COMPRESSION SPRING; A SUBSTANTIALLY FLAT CASING SECURED TO SAID FRIST END OF SAID BODY AND HOSUING SAID RACK PORTION OF SAID ROD; A DOUBLE SEGMENTAL GEAR EMBODYING A FIRST TOOTHED SEGMENT IN MESH WITH SAID RACK PORTION OF SAID ROD AND A SECOND TOOTHED SEGMENT OF SMALLER RADIUS THAN SAID FIRST SEGMENT AND ANGULARLY SOLID THEREWITH, SAID DOUBLE SEGMENTAL GEAR BEING ROTATABLY CARRIED WITHIN SAID CASING; MEANS CARRIED BY SAID CASING TO GUIDE SAID ROD AND TO MAINTAIN THE RACK PORTION THEREOF IN MESH WITH SAID FIRST TOOTHED SEGMENT OF SAID DOUBLE SEGMENTAL GEAR; A MOVABLE CUTTING BLADE ROTATABLY CARRIED BY SAID CASING AND PROJECTING OUTWARDLY THEREFROM; A TOOTHED SECTOR SECURED TO SAID MOVABLE CUTTING BLADE CO-AXIALLY THERETO TO MESH WITH SAID SECOND TOOTHED SEGMENT OF SAID DOUBLE SEGMENTAL GEAR; A FIXED CUTTING BLADE SECURED WITHIN SAID CASING AND PROJECTING OUTWARDLY THEREFROM FOR COOPERATION WITH SAID MOVABLE CUTTING BLADE; A SWITCH CARRIED BY SAID BODY AT SAID SECOND END THEREOF; A ROD LONGITUDINALLY CARRIED BY SAID BODY TO ACTUATE SAID SWITCH; AND A SPRING-LOADED TRIGGER PIVOTED TO SAID BODY NEAR SAID FIRST END THEREOF TO ACTUATE SAID ROD. 